GB 2163747 describes that benzimidazole derivatives having the formula (A): ##STR3## wherein each of R.sup.10 and R.sup.11 is hydrogen or a lower alkyl group, and one of R.sup.12 and R.sup.13 is a halogen, trifluoro methyl, a lower alkyl group, a lower alkoxy group, a lower alkoxycarbonyl group or amino, are effective as anti-ulcer agents showing H.sup.+ +K.sup.+ ATPase inhibitory action.
EP234690A describes that sulfoxides having the formula (B): ##STR4## wherein each of R.sup.14 and R.sup.5 is hydrogen or a lower alkyl group and each of R.sup.16 and R.sup.17 is hydrogen, a lower alkoxy group or a lower alkyl group, are effective as anti-ulcer agents showing H++K+ATPase inhibitory action.